[time-nuts] T-Bolt with dead PPS and 10MHz output - how to repair?

Alexander Kurpiers a.kurpiers at nt.tu-darmstadt.de
Sat Apr 7 19:05:48 UTC 2012


I got a Thunderbolt on Ebay and it appears to be running fine - just the PPS and 10MHz outputs stay silent.
But it seems to lock (according to the monitor program) and the site survey was completed without issues.
I'm pretty sure the OCXO works fine, otherwise it would not say it is locked would it?

After opening the Thunderbolt I could see that the 74AC04 driving the PPS output died and I see the PPS pulse on the input to this chip.
Unfortunately the 10MHz output does not seem to be an easy one: it only shows some 80Hz noise and no 10MHz.
In my case, the final output buffer U20 is a CLC453 (http://www.national.com/opf/CL/CLC453.html) - but it appears to be ok, at least I have the same strange signal on the input, too.

I'm a bit lost without schematic now...

Regards,

Alexander DL8AAU/AB0CF

 






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